Shmidtz's response is particularly insightful in demonstrating how utilitarians can benefit from using the deontological tool of rights claims, and to a lesser extent, how deontologists might benefit from using utilitarian calculations. In both cases, the side that benefits benefits from what they believe to be a useful fiction: something they do not necessarily believe in fully, but that serves as a valuable conceptual tool nonetheless.

[S]ome people believe in rights and some don't. Of the people who believe in rights, some people are content merely to assert that we have the rights they think we have. Other believers in rights want to produce an argument. To produce an argument for rights, they have to start from premises that do not beg the question by assuming the rights for which they meant to argue. So, suppose one honestly came to the conclusion that the answer to Singer's question is, no: at least some kinds of interference, say interfering with people wanting to vote, people wanting an abortion, people wanting to buy and sell marijuana, or whatever you like, indeed do more harm than good. That starts to approximate a real argument that we have reason to treat people as having a right not to be interfered with in those ways. I realize that confirming the premise that interference does net harm does not clinch the conclusion that there is a right against such interference, but I wasn't saying it does. I'm just saying that confirming the premise accomplishes quite a bit beyond merely asserting rights. Deontologists would not be impressed with an argument that begins this way, but actually, I think they should be, because the point is that we could start from utilitarian premises and still end up moving in the direction they think is called for by their deontological premises.

I am not a utilitarian, but I play one on TV. Not really, but I do take utilitarian arguments seriously, because even though I am not persuaded to buy into the theory wholesale, I think utilitarian arguments tend to be the least question-begging kind of argument for conclusions about rights, and also for sorting out why I should believe in one rights-claim rather than another, in cases where I have no particular ax to grind. (Drug legalization would be one such case.) One thing I like about utilitarians as such. They grasp what should be a plain fact: that showing that some people don't have rights does not begin to imply that anyone else has a right to interfere. More controversially, I agree with utilitarians that to justify a claim to have a right to interfere, one has to show that interference does more good than harm. I do not agree that this is sufficient. Nonutilitarians will grant me this point. Utilitarians won't, and I won't blame them for refusing to concede. To engage utilitarians, I would have to argue from their own premises (because that's where they are). I would have to argue that making it legal for people to sacrifice one to save five would systematically have bad consequences, and so is not to be systematically permitted even from a utilitarian perspective.

Sometimes too we have occasion to defend the propriety of observing the general rules of justice by the consideration of their necessity to the support of society. We frequently hear the young and the licentious ridiculing the most sacred rules of morality, and professing, sometimes from the corruption, but more frequently from the vanity of their hearts, the most abominable maxims of conduct. Our indignation rouses, and we are eager to refute and expose such detestable principles. But though it is their intrinsic hatefulness and detestableness, which originally inflames us against them, we are unwilling to assign this as the sole reason why we condemn them, or to pretend that it is merely because we ourselves hate and detest them. The reason, we think, would not appear to be conclusive. Yet why should it not; if we hate and detest them because they are the natural and proper objects of hatred and detestation? But when we are asked why we should not act in such or such a manner, the very question seems to suppose that, to those who ask it, this manner of acting does not appear to be for its own sake the natural and proper object of those sentiments. We must show them, therefore, that it ought to be so for the sake of something else. Upon this account we generally cast about for other arguments, and the consideration which first occurs to us, is the disorder and confusion of society which would result from the universal prevalence of such practices. We seldom fail, therefore, to insist upon this topic.

But though it commonly requires no great discernment to see the destructive tendency of all licentious practices to the welfare of society, it is seldom this consideration which first animates us against them. All men, even the most stupid and unthinking, abhor fraud, perfidy, and injustice, and delight to see them punished. But few men have reflected upon the necessity of justice to the existence of society, how obvious soever that necessity may appear to be.